Corn Seed Survival: The Effect of Planting Date

May 5, 2005 12(9):61-62

Joe Lauer, Corn Agronomist

With the cool weather we have been having farmers are concerned about stand establishment
of corn. Over the last couple of weeks wide-spread areas of the state have been
frosted a number of times. Although 26% of corn crop had been planted by May 1,
only 1% had emerged so little damage should be expected to these fields due to frost.
Field conditions in general have been fairly good. With a little warm weather the
corn seed planted should make good progress emerging over the next few days.

Typically when seeding a corn field, extra seed (~10%) is dropped to allow for seed
death due to predation, pest damage, soil crusting, problems with emergence, etc.
Some agronomists question this practice because of the advances in seed treatment
technology that have occurred over the past decade. Emergence of corn seed in Wisconsin
is challenging because of the cool, wet soil conditions we typically experience
at planting. This article summarizes the effect of planting date on corn seed survival.

During the growing seasons between 2000 and 2004, two hybrids were planted (full-
and short-season) on different dates into a Plano silt loam soil at Arlington, WI.
Each 8-row plot was over-seeded and at V6 the plants emerged were counted and then
thinned back to a final harvest stand of about 30,000 plants/A. The number of plants
that had emerged at V6 for each row was divided by the number of seeds planted for
each row and multiplied by 100 to calculate percent survival.

In all years, planting date affected corn seed survival. April planting dates had
seed survival ranging from 64 to 95% and averaged 79% (Table 1). Seed survival between
May 1 and May 15 ranged from 62 to 92% (average = 83%), between May 16 and May 31
was 80 to 96% (average = 88%), and during June was 84 to 98% (average = 92%). April
planting dates were riskier for survival than May planting dates, but often conditions
could cause just as much plant death during May as April. In fact, during 2004 the
lowest average seed survival occurred on May 20.

In 3 of 5 years hybrids differed for seed survival. In 2 of 5 years interactions
between planting date and hybrid occurred where hybrids had different amounts of
survival depending upon the planting date.

Some guidelines for corn seed survival as affected by planting date:

Over-seeding your target population by 10% is still a reasonable recommendation
for Wisconsin farmers for all planting dates.

June planting dates have better seed survival than May dates followed by April dates.
Although, good and poor survival can be seen on any planting date during April and
May.

Seed treatments are important and may help when planting early, since there is inherently
more stress in Wisconsin's cool, wet soils.